Betaine is a valuable compound which is used in animal fodders, as well as in pharmaceutical and cosmetic applications.
Betaine occurs in the roots, seed and stems of a great variety of plants. Its concentration in sugar beet is relatively high, 1.0% to 1.5% on a dry solids basis. When sugar beet is processed for the recovery of sucrose, betaine concentrates in the molasses. Beet molasses usually contains from 3% to 8% of betaine calculated on a dry solids basis.
Betaine is an amphoteric compound having the formula: ##STR1##
It is known to recover betaine from beet molasses, rest molasses or vinasse by ion exchange, by crystallization as a hydrochloride, by extraction with an organic solvent, or by chromatography.
A chromatographic method for the recovery of betaine is described in U.S. Pat. No. 4,359,430. This method is a chromatographic process in which molasses which contains betaine, such as beet molasses, is introduced to the top of a column containing a polystyrene sulphonate cation exchange resin in alkali metal form at a flow rate of 0.5 to 2.0 m.sup.3 /h/m.sup.2. Elution with water is carried out for the recovery of betaine, sucrose and rest molasses from the downstream side of the resin bed.
Simulated or pseudo-moving bed chromatography, i.e., a multi-step separation process in which a solution containing two or more substances to be separated is circulated with respect to a stationary phase, has been used for the separation of two components, such as glucose/fructose from high-fructose syrups or sucrose/rest molasses from molasses.
The first commercial simulated moving bed method was described in U.S. Pat. No. 2,985,589. U.S. Pat. No. 4,404,037 describes a simulated moving bed technique wherein carbon is used as an adsorbent for the recovery of sucrose from molasses. U.S. Pat. Nos. 4,426,232 and 4,533,398 describe similar methods wherein zeolite is used as an adsorbent. U.S. Pat. No. 3,997,357 describes a continuous method for the recovery of sucrose from molasses, and U.S. Pat. Nos. 4,519,845, 4,332,623 and 4,405,455 methods for the separation of sucrose from molasses. U.S. Pat. No. 4,461,649 describes a method for simulated countercurrent separation of sugars. A summary of these separation methods is presented in e.g. Food Engineering (Anon) 1983 55 (5) p. 154, and Sugar y Azucar (1987) August, p. 27 and 29 (U. Bhawarda).
Commercial simulated moving bed methods are also described in U.S. Pat. No. 3,732,982, U.S. Pat. No. 4,412,866, and Chemical Engineering 1981 August/September p. 389 to 393 (P. Barker et al.). In EPO application No. 0279 946, a simulated moving bed method is described for the separation of beet molasses into three or more fractions.
However, the recovery of betaine is not disclosed and the performance of the method is low.
Beet molasses contains sucrose, betaine, salts, amino acids and other organic and inorganic components. It is highly desirable to recover betaine in the same cycle as sucrose. However, this has not been possible previously through the use of simulated moving bed methods.
In previous methods for the recovery of betaine from beet molasses using chromatographic methods, the separation capacity and/or the dry content of the separated fractions has been low.
It is therefore an object of the present invention to separate sucrose, betaine, and rest molasses using a chromatographic technique in which all three fractions are recovered during the same cycle.
It is another object of the present invention to recover a betaine-rich fraction by a single fractionation step with no post-fractionation required.
It is another object of the present invention to effect a high performance separation of betaine so that the separation capacity is high, the yield of the different components in the product fractions is high, and the consumption of eluent water is low.